What is My Roof's Pitch?
When it comes to having a roof installed or repaired one of the first questions asked will be what the pitch of your roof is. The pitch, also called slope, is the amount of angle to your roof or the amount that it increase in height for every foot it runs.
WHY DOES THE PITCH OF A ROOF MATTER
The pitch of the roof is important because it can have a big impact on how easily the work is done. A relatively low pitch can be easily walked upon while a higher pitched roof may require the roofer to take special precautions to avoid slipping and falling. On steep roofs boards may need to be attached to the decking of the roof so that a person can walk more safely. This makes for a slower (and more expensive) roof installation since the boards will have to be attached and removed as the roofer works down to the eaves.
HOW DO YOU DETERMINE THE PITCH OF A ROOF
Use a level and measuring tape and determine how much rise (or drop) the roof has over the course of 12 inches. Mark 12 inches on the level and then measure how many inches it is from that spot down to the roof. (Don't forget to make sure you are holding it level or your measurement may be off.) In our picture the roof raises 8 inches for each 12 inches of length. This is referred to as 8 and 12 or 8-12 pitch which is a moderately steep roof.
The most accurate way to determine the roof pitch is to do so on the bare decking (or underlayment) of the roof. The reason for this is some types of roofing materials may give you an inaccurate reading such as asphalt shingles when they are curled or buckling. If it is not possible to measure on the bare decking you can always take the measurement from inside the attic on the underside of the decking.